The gene encoding p202, an interferon-inducible negative regulator of the p53 tumor suppressor, is a target of p53-mediated transcriptional repression.

The p53 tumor suppressor protein regulates the transcription of regulatory genes involved in cell cycle arrest and apoptosis. We reported previously that overexpression of p202, an interferon-inducible negative regulator of cell growth, negatively regulates the transcriptional activity of p53. Now we identify the gene encoding p202 as one whose mRNA and protein expression decrease in cells following the expression of wild-type, but not mutant, p53. Furthermore, the levels of p202 also decrease after exposure of cells to ultra violet light, which correlate with increase in the levels of p53. We report that the sequence-specific DNA binding of p53 to the 5'-regulatory region of the 202 gene contributes to the transcriptional repression of the 202 gene. Interestingly, overexpression of p202 in cells induced to undergo p53-dependent apoptosis significantly delays this process, indicating that the negative regulation of the 202 gene by wild-type p53 is important to potentiate apoptosis.